Metasurface with Nanostructured Ge2Sb2Te5 as a Platform for Broadband-Operating Wavefront Switch

Chulsoo Choi, Seung Yeol Lee, Sang Eun Mun, Gun Yeal Lee, Jangwoon Sung, Hansik Yun, Jong Heon Yang, Hee Ok Kim, Chi Young Hwang, Byoungho Lee

Research output: Contribution to journalArticlepeer-review

91 Scopus citations

Abstract

Broadband-operating active devices within a small-footprint are highly on demand in various nanophotonic fields such as fiber-optic communication systems and chip-based integrated optical circuits. As pioneering approaches, diverse platforms of active metasurfaces (AMs) have been proposed due to their superior tunable functionality and ultra-compact size. However, most of previous researches provide only limited operating bandwidth because they generally rely on resonant light–matter interaction between active material and plasmonic antenna. In this study, an active wavefront switching metasurface that can operate over 500 nm bandwidth at near-infrared spectral bands is experimentally realized by utilizing nonresonant U-shaped Ge2Sb2Te5 nanoantennas. Two different sizes of the U-shaped antenna are designed to exhibit large transmittance contrast and their optical phases are determined by imposing the orientation angle variation. As an example of the functionality, anomalous refraction angle switching and dispersionless active hologram are demonstrated. The devices provide high signal-to-noise ratio (>7 dB) for overall operation bandwidth. It is believed that the proposed AMs can be an innovative platform for real device application thanks to their not only broadband and low-noise operation but also fast speed, low power consumption switching within a small-footprint.

Original languageEnglish
Article number1900171
JournalAdvanced Optical Materials
Volume7
Issue number12
DOIs
StatePublished - 18 Jun 2019

Keywords

  • beam steering
  • GST
  • holography
  • metasurface
  • phase change material

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